The invention relates to an apparatus for measuring, in a tire testing machine, radial and axial forces at a wheel consisting of a pneumatic tire and a rim.
More particularly, an apparatus is provided wherein the pneumatic tire rolls, during the measuring run, on a roll-off base, particularly a testing drum. This apparatus also has a measuring axle on which the wheel is rotatably mounted during the measuring run, and force measuring devices for measuring the radial and axial forces.
In order to determine the wear, the stability under load and the fatigue strength of vehicle tires, vehicle tires must be tested on corresponding tire testing machines under the same or even under more extreme conditions than those existing when the tire is on the vehicle. By means of the tire testing machine, all load possibilities must be simulated. In this case, the tire is subjected to radial and axial loads, at a variable inflation pressure and at a variable driving speed. The purpose is to determine, during the test run, the radial and axial forces that occur at the tire.
As the roll-off base, which serves for simulating the road, a continuous belt that is guided via pulleys may be used, or a testing drum, such as it is known from Automobile-Industrie, 2/71, Pages 85 to 90. Also known are measuring devices, particularly in the form of so-called dynamo hubs, which are arranged in the area of the motor vehicle axle or also of a measuring axle at the tire testing machine (Published German Patent Application Nos. 21 04 003 and 22 14 256). In the case of these dynamo hubs, which require high manufacturing costs, several strain gauge bridge circuits are used in order to determine radial and axial forces as well as moments that occur during the measuring run.